Current constant temperature circulators have many disadvantages, only some of which are described herein. Generally, conventional constant temperature circulators include a stainless-steel box enclosing various electrical components. Circulation and heating components depend unprotected from the box. One disadvantage of the box construction is that the box is made of multiple components and as a result tolerance stack up is a prevalent issue. In fact, significant efforts have been expended to reduce such tolerance issues, considerably raising the costs to manufacture. Another disadvantage is the lack of protection for the depending components (i.e., heating element, pump/circulation and temperature sensor) not only such that such components are not damaged, but also that the contents of any container into which the circulator is inserted are not damaged. Current attempts to address this disadvantage are multiple piece stainless steel components that face the same tolerance stack up issues mentioned herein. Accordingly, there is a need in the art for constant temperature circulators that overcome the disadvantages identified herein, among others, including, without limitation, reduces the cost of manufacture, achieves improved functionality with far fewer parts, improves reliability because of reduced tolerance stack up, prevents contact between the contents of a container into which the circulator is inserted and the moving or heating elements of the circulator, provide flow adjustment with respect to multiple outlets and a bidirectional pump for adjustable outlet flow and external circulation.